938 Ts Littorina htorea Introduced or Indigenous? (November, 
for believing the shell to have been recently and accidentally in- 
troduced, but it acquires additional force taken in connection 
with other facts which point to the same conclusion. 
But granting fora moment that the shell did exist in Nova 
Scotia previous to this century—where it must have been con- 
fined if it was in America at all—what an anomalous condition of 
life we have. At present, as we follow its progress southward, 
we find it growing more and more abundant. The writer has 
very frequently noticed its distribution on the Southern New 
Brunswick coast, but it there occurs in nothing like the profusion 
in which he has seen it at Nahant, Mass., or Newport, R. I. In 
these two places, and they are like other localities in these two 
States in this respect, it literally covers the rocks, the native spe- 
cies becoming comparatively rare. What is the meaning of the 
fact that it becomes more abundant southward? Can it mean 
anything else than that (within certain limits) as it goes south it 
meets with a more and more congenial habitat? If this be so, 
and we can see no other conclusion, it shows that L. /torea 
thrives better in warmer water than that of the coasts of Nova 
Scotia and New Brunswick, and therefore that the natural home 
of the species, or the place where it originated was in warmer 
water than that of Acadia. This conclusion is strengthened by 
the fact of its non-occurrence in Greenland or Labrador, to both 
of which places it should have been carried by the same agencies 
which took Z. palliata there. The latter is certainly a mor 
northern species than the former, and it may be that the condi- 
_ tions of life in these two places are altogether unsuited to the 
more southern Z. ditorea, in which case it could certainly not 
have been carried from one continent the other by way of Green- 
land. Zf then L. itorea existed upon the Nova Scotia coast a5 
(in the sense in which we are using the word) an indigenous SP 
cies, it was existing without spreading under comparatively un- 
favorable conditions of temperature, etc., while favorable condi- 
tions were waiting for it not far to the southward. Surely the 
agencies which took it from one continent to the other (if gee! 
rally introduced) could have carried it to the New England coas : 
Is it not more natural to suppose, what so many of the facts m 
dicate, that the warmer watersʻin which it thrives the gee? 
_ like those of its home, and that its home is in the waters of 
English coast, which we know to be so much warmer than 
‘Scotia? l 
